Structural Analysis of a Novel Class of R-M Controller Proteins: C.Csp231I from Citrobacter sp RFL231

JOURNAL OF MOLECULAR BIOLOGY

卷:409

Article

McGeehan, J. E.¹  Streeter, S. D.¹  Thresh, S. -J.¹  Taylor, James E. N.¹  Shevtsov, M. B.¹  Kneale, G. G.¹ 

[1] Univ Portsmouth, Biophys Labs, Inst Biomed & Biomol Sci, Sch Biol Sci, Portsmouth PO1 2DY, Hants, England

关键词: restriction-modification;    helix-turn-helix;    X-ray crystallography;    small-angle X-ray scattering;    analytical ultracentrifugation;   

DOI  :  10.1016/j.jmb.2011.03.033

来源: Elsevier

【 摘 要 】

Controller proteins play a key role in the temporal regulation of gene expression in bacterial restriction-modification (R-M) systems and are important mediators of horizontal gene transfer. They form the basis of a highly cooperative, concentration-dependent genetic switch involved in both activation and repression of R-M genes. Here we present biophysical, biochemical, and high-resolution structural analysis of a novel class of controller proteins, exemplified by C.Csp231I. In contrast to all previously solved C-protein structures, each protein subunit has two extra helices at the C-terminus, which play a large part in maintaining the dimer interface. The DNA binding site of the protein is also novel, having largely AAAA tracts between the palindromic recognition half-sites, suggesting tight bending of the DNA. The protein structure shows an unusual positively charged surface that could form the basis for wrapping the DNA completely around the C-protein dimer. (C) 2011 Elsevier Ltd. All rights reserved.

【 授权许可】

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